Stephen Lawrence's mother Doreen Lawrence speaks to the media outside the Old Bailey in central London Tuesday Jan 3 2012, following the conviction of Gary Dobson, 36, and David Norris for the racist murder of her teenaged son in 1993. The case _ which has seen multiple court cases but no convictions until now _ led to strong criticism of London's Metropolitan Police and resulted in an investigation that found that the force was "institutionally racist".

LONDON — A young black man lay dying in a south London bus stop. His friend called frantically for help while a gang of white teenagers who had stabbed him ran off. Two members of that gang were sentenced Wednesday for the 1993 murder of Stephen Lawrence, but three more remain at large.

Judge Colman Treacy Wednesday sentenced Gary Dobson to at least 15 years and 2 months in jail, and David Norris to at least 14 years and 3 months for the murder of the 18 year old, and urged police to continue looking for new leads in the case.

Police, who have been accused in the last two decades of incompetence and racism in the way they handled the murder inquiry, vowed Wednesday to continue to hunt for the remaining killers.

"The other people involved in the murder of Stephen Lawrence should not rest easily in their beds," said Bernard Hogan-Howe, commissioner of London's Metropolitan Police.

The saga of Lawrence's murder, and his parents' long quest for justice in the face of police indifference, has for many come to symbolize Britain's lingering racial trauma.

It has embarrassed Scotland Yard, which was found by an official inquiry to be guilty of systematic racism. And while Lawrence's family said it was pleased with the convictions, it said justice will not be served until all the killers face trial.

Lawrence's father Neville said the sentencing of Dobson and Norris for his son's murder was "only one step in a long, long journey."

Dobson and Norris were part of a notorious gang that terrorized part of south London, and many people told police in the days following Lawrence's death who his killers were likely to be.

But the police failed to act until Lawrence's parents held a news conference to criticize the way the police had handled the case. It was the first salvo in a long battle the Lawrence family were to fight with police and courts.

A few days after the news conference, police arrested five men — brothers Neil and Jamie Acourt, Norris, Dobson and Luke Knight. But police lost blood-soaked tissues found near the site of the attack, and failed to search the Acourts' house properly for weapons. Police eventually charged two with murder, but the state abandoned the case, saying there was insufficient evidence.

Lawrence's family, mistrustful of state prosecutors, brought a private prosecution against the same five men. Two were released before the trial, and the case against the remaining three collapsed after a judge ruled again that the evidence was inadmissible.

British law at the time said that a person could not stand trial twice for the same crime — having been acquitted, it seemed impossible that any of the three would face trial for Lawrence's death.

In 1997 the Daily Mail newspaper — a popular tabloid — named all the five men initially arrested over Lawrence's murder on its front page with the headline "Murderers. The Mail accuses these men of killing. If we are wrong, let them sue us."

None of the men ever did, though Neil Acourt later changed his name to Neil Stuart, fearing reprisals over the Lawrence case.

The public outcry that followed the Daily Mail coverage led Home Secretary Jack Straw to order a public inquiry. The report by William Macpherson was damning. The Metropolitan police, it said, were "institutionally racist," and failed to investigate Lawrence's murder properly because they were hostile to London's black community.

The Labour Party government also scrapped the "double jeopardy" law that prevented people being tried twice for the same crime. A few years later a private forensics firm discovered tiny amounts of blood, hair and clothes fibers from Lawrence on clothes belonging to Dobson and Norris. The new evidence was enough to convince the director of public prosecutions to bring the case to court.

The three other men are still free.

Britain's Court of Appeal said Wednesday that if prosecutors wanted to bring charges against the men, they would first have to prove they had found new and compelling evidence and ask the Court of Appeal to quash Neil Acourt and Luke Knight's earlier acquittals so they can stand trial again. No such request has been made.

The sheer length of time it has taken to prosecute the case has taken its toll. Lawrence's parents divorced six years after his death.

And Britain's police forces still struggle to convince ethnic minorities that they handle cases with sensitivity. The parents of Indian student Anuj Bidve, who was shot and killed by a white man on a night out in Salford, north east England on Dec. 26, complained that they learned about their son's death from Facebook before British police contacted them.